Got a FB post the other day from a friend who asked the following question:
Got a lens Q that I’m trying to figure out.
When going FF, is it always more beneficial to go the L series lenses? Reason I ask is I’ve read some reviews that some non-L series lenses are just as good or slightly better than their more expensive counterparts.
Well, it’s not a simple question. The short answer is "no, L-series are not a requirement".
The longer answer is that you should buy lenses that fill the need you have, and once you’ve decided the type/FL/aperture/etc that you need, research it to death until you decide on the one that best suits you.
I’ve got eight lenses, and six of them are L-series, so it may sound like I’m agreeing with the premise of the question, but I’m still not, really I bought my 28-70L as my first lens (to go on my 10D) because it was a screaming bargain, my 70-200/2.8L IS replaced my Sigma 70-200 because I needed the IS, my 14L and 35L are the only lenses that fitted exactly what I needed, the 85/1.2 is the sheer awesomeness that is the 85/1.2. My Sigma 120-300 is a great lens (and unique), while my TS-E 90 isn’t a L-series but is both insanely sharp and obviously does something no other lens does.
So the lesson is – pick the lens that works best for your purpose and your budget, don’t be seduced by the red ring.